This invention is an improvement on an earlier invention disclosed in abandoned application Ser. No. 756,358 of Henry I. Smith for Enhancing Epitaxy and Preferred Orientation, and relates in general to improving the crystallographic quality of solid films grown on the surfaces of solid substrates, and more particularly to improved means for obtaining epitaxial or preferred orientation films on solid substrates, both crystalline and amorphous.
Much of modern technology makes use of thin solid films on the surfaces of solid substrates. Epitaxial and preferred orientation films are particularly important, notably in microelectronic devices, thin film optical devices and solar cells. Thus, improved methods of preparing epitaxial and preferred orientation films are of great importance.
The principle involved in the earlier invention, referenced above, was to use a plurality of artificial defects, formed at predetermined locations at the surface of a solid substrate, to determine, control or influence, by means of the geometric arrangement of the adjacent defects, the crystallographic orientation of a film deposited at said surface. The said artificial defects were either (1) artificial point defects or (2) artificial surface relief structure. The method disclosed in said earlier patent has been named "graphoepitaxy" (see "Crystallographic Orientation of Silicon on an Amorphous Substrate Using an Artificial Surface Relief Grating and Laser Crystallization", by M. W. Geis, D. G. Flanders and H. I. Smith, to be published in Applied Physics Letters Jul. 1 , 1979). The name is derived from the Greek ("grapho" meaning to write or incise) and was chosen to convey the principle of using an artificially created surface pattern to induce epitaxy. The present invention concerns (1) a particular implementation of graphoepitaxy in which the influence of artificial defects on the crystallographic orientation of a film is induced or enhanced by irradiating the film with the electromagnetic or acoustic radiation or energetic particles, including electrons; (2) a method whereby crystallographic orientation is determined, controlled or influenced by the geometric arrangement of a single defect (that is, its position, orientation and geometric form); and (3) a particular implmentation of graphoepitaxy in which the relief structure includes facets that intersect at approximately 70.5.degree. and 109.5.degree..